Whenever motor and other vehicles are operated in combination during the time that lights are required, any light, except tail lights, which by reason of its location on a vehicle of the combination would be obscured by another vehicle of the combination need not be lighted, but this section does not affect the requirement that lighted clearance lights be displayed on the front of the foremost vehicle required to have clearance lights or that all lights required on the rear of the rearmost vehicle of any combination shall be lighted. (ORC 4513.08)